Fuel control apparatus



Sept; 1960 c. E. HAJNY 2,953,198

FUEL CONTROL APPARATUS Filed Aug. 23, 1956 2 Sheets-Sheet 1 INVENTOR.

[fad/026s 15. Ha, BY W eMa/dnwh United States Patent f FUEL CONTROL APPARATUS Charles Hajny, Milwaukee, Wis., assignor to Baso Inc., Milwaukee, Wis., a corporation of Wisconsin Filed Aug. 23, 1956, Ser. No. 605,731

Claims. (Cl. 158131) This invention relates in general to an apparatus for the control of gaseous fuel and more particularly to apparatus for controlling the flow of gaseous fuel to main and pilot burners of fluid fuel burning apparatus in a manner to afford improved efiiciency.

In modern control of gaseous fuel flow, many types of so called self-powered or self-generating systems are available to control the fuel flow to gaseous fuel burners. One type of power source for the self-generating systems is a thermoelectric generator which may be heated by a pilot burner to supply electric energy for controlling various combinations of safety shut-off valves and main burner valves. The problem of keeping .pilot gas consumption low has become increasingly difficult due to larger and larger power requirements in self-generating systems requiring larger output generators, which in turn require substantial generation of heat to supply the necessary power. This high heat is particularly objectionable, for example, in the summer time situation in domestic furnaces where only pilot gas is flowing, and the high B.t.u. consumption necessary to heat the large generators for operating the self-generating systems during operating cycles may be much more expensive to maintain than desirable during such a standby situation.

There are a number of applications wherein the B.t.u. consumption (as determined by pilot size) is relatively unimportant during operating cycles, but where it is greatly desirable to reduce the B.t.u. consumption of the pilot burner during long standby periods. As an example, in a furnace for domestic heating applications, the size of the pilot flame may have to be relatively large in winter but as aforestated, preferably should be relatively small in summer for reasons of economy. There are many advantages in the pilot being large in winter, and in many applications a large pilot is a necessity at all times that the main burner is to be ignited because of the strong secondary air currents created by combustion of the main burner which would tend to snuff a small pilot. On the other hand, in most domestic heating systems it is greatly desired that a constant burning pilot should remain ignited all through the summer to prevent rust and corrosion of the parts within the heating chamber, to afiord a constant check on the workability of the controls of the furance, md to be instantly ready for use without the necessity of a service call to light the pilot.

Water heaters, commercial and industrial furnaces, etc. also may be advantageously supplied with low consumption standby pilots similar to those aforedesor'ibed for domestic furnaces. A domestic cooking range presents an added problem in that it is normally in standby situation with the main burner off. For example, the percentage of total time of operation of the main burner in a range is generally very low, yet instant ignition is required by the housewife.

In ranges particularly and in the other applications too, heretofore, the limiting factor for the minimum flow rate of fuel supplied to the pilot burner has often been determined by the flow rate that will support ignition of the Patented Sept. 20, 1960 main burner without snufling out of the pilot. This flow rate is often considerably greater than the amount of fuel flow that will support a stable flame at the pilot burner when the main burner is not ignited. It is desirable to maintain the apparatus on a low flow standby pilot with the aforementioned lowest flow rate for reasons of economy. Such a low flow rate pilot system that utilizes a flow rate affording a low consumption flame that is insuflicient to ignite the main burner is safe only if an interlock is provided that affords a higher amount of pilot flame for and during ignition of the main burner. A system incorporating the above concepts would afford a greater economy than heretofore possible.

It is a general object of this invention to provide an apparatus affording an increased efiiciency by providing a relatively large constant ignition flame at any general operating period and which provides a low B.t.u. consumption flame in standby settings for periods of non-use.

Another object of the invention is to provide an apparatus of the aforementioned general characteristics wherein fuel may flow to a main burner only when an ignition burner is in a high flame position, thus preventing attempted ignition of the main burner by a low consumption flame that is too small to support ignition of said main burner.

A further object of the invention is to provide an apparatus as above characterized having main and pilot .burners, main burner flow control means having flowpermitting and flow-preventing positions, flow control means for said pilot burner, the latter flow control means having a flow-preventing position and high and low flowpermitting positions, and interlock means associated with both said flow control means preventing the movement of the main burner flow control means to its flow-permitting position when the pilot burner flow control means is in said low flow-permitting position to thereby provide a safe and economical heating apparatus.

A further object of the invention is to provide an apparatus as above described having generating means responsive to a flame at the pilot burner, safety shut-off means and main burner flow control means both energizable by said generating means, said generating means delivering different levels of electrical energy responsive to the various heat levels of the pilot burner as determined by the position of said pilot burner flow control means, said generating means affording suflicient electrical energy to energize both said safety shut-off means and said main burner flow control means when said pilot burner flow control means is in said high flow-permitting position, said generating means delivering insufficient energy to energize both said safety shut-off and main burner flow control means when said pilot burner flow control means is in said low flow-permitting position, and electrical interlock means preventing energization of the main burner flow control means and permitting continued energization of the safety shut-off means when the generating means affords insuflicient energy to energize both the main burner flow control and safety shut-off means, thereby aiford ing safety shut-off control as long as the pilot burner remains ignited.

A further object of this invention is to provide the apparatus as aforementioned with reset means for resetting the safety shut-ofl means to a flow-permitting position and interlock means for cooperation with the safety shut-01f means and the pilot burner flow control means, said interlock means preventing resetting of the safety shut-01f means except when the pilot burner fiow control means is in its high flow-permitting position to thereby aflord suflicient fuel for initial ignition of said pilot burner, and following ignition, permitting movement .of the pilot burner flow control means to a low or reduced flow-permitting position providing sufiicient fuel to main;

tain a stable flame but insufficient for said initial ignition of the burner.

A further object of this invention is to provide apparatus as above described having a plug valve therein that affords flow interruption means for prevention of fuel flow to'the main burner during the reset operation of the safety shut-off means and also simultaneously permits the high ignition'fuel flow to the pilot burner. V V

'A further specific object of this invention is to provide an apparatus of the above type wherein the safety shut-.ofi means is operable to prevent all fuel flow to both the main :and pilot burners upon pilot, outage irrespective of whether the pilot burner flow control means is positioned in its high flow-permitting or its low flowpermitting positions.

Another object of the invention is to provide a device as above characterized having thermoelectrically powered safetyshut-oif and main burner .valves with a high limit switch connected in circuit with both said valves to cause both valves to become .deenergized to thereby prevent fuel flow upon the occurrence of an abnormal situation, said arrangement protecting against a hung ,or leaky safety shut-off valve.

Still another object of the invention isto provide an apparatus which is compact, extremely sturdy for long field life, easy fabricated and assembled, and is otherwise well-adapted for the purposes for which it was designed. 4 p The novel features that are characteristic of the inven- .tion are set forth with particularity in the V appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof will best be understood by the following description of specific embodiments when read in connection with the accompanying drawings, in which;

b Figure 1 is a view partially in section of the improved control apparatus embodied in the fuel control system, portions of the apparatusand of the system being shown semi-diagrammatically;

Figure 2 is a fragmentary sectional view of an alternative form of the fuel control apparatus;

Figure 3 is a fragmentary portion of a top plan view of the fuel control device depicted in Figure 1;

Figure 4 is a fragmentary sectional view of the plug valve shown in Figure l in the winter position;

Figure 5 is a view similar to Figure 4 showing the plug valve in the high pilot and reset position;

Figure 6 is a view similar to Figures 4 and 5 showing the plug valve in the summer or standby low pilot position;

Figure 7 is a viewsimilar to Figures 4, 5 and 6, showing the plug valve in the 100% off position; and

Figure 8 is a fragmentary sectional view ofanother alternative form of the fuel control apparatus.

While a specific control system is shown and described in connection with a pilot burner and main burner for burning gaseous'fuel in adomestic furnace, it is to be understood that the invention is not limited to this use, but it is adapted for use equally well wherein it is desired and/or required that there be a relatively large constant burning ignition flame during operating cycles and in which a small constant burning flame is desired during standby periods.

Referring now to Figure l, the new flow control apparatus 10 is adapted to control the flow of fluid fuel to a main burner 12 and a pilot burner 14. The apparatus lzis connected between a suitable source of fuel (not shown) and the burners 12 and 14, there being a fuel supply line 16 leading from the fuel source to an V inlet2l) ofgthedevice'. Separate control ofthe main and pilotburners is provided by the control device 10 and separate supply'pipes are provided to said burners from the device such as a supply line 15 leading from a pilot outlet 22 to the pilot burner 14.and supply line '17 lleading from a main burner outlet 21 to the main burner The control apparatus shown in Figure l is of the self-powered type and to that end the pilot burner 14, when ignited, is adapted to impinge a flame upon a suitable thermoelectric generator 18 which when heated supplies energizing power through suitable circuitry for operating the safety shut-off means 40 and main burner flow control means 50 within the control device 10 in a manner as shall be more fully explained later. The selfpowered system includes a suitable highlimit theremostat 60 and a cycling thermostat 70 interposed in the circuitry bet-ween the generator 18 and the electrical components in the device 10 for purposes appearing hereinafter.

The major components'within the device 10 comprise the safety shut-off means 40, the plug valve means 25 and the main burner flow control means 50. The control device 10 may be formed with an outer casing 19 surrounding a plurality of chambers 30, 31, 32, 33, the inlet 20 leading into chamber 30, the main burner outlet 21 leading from chamber 33, and the pilot outlet 22 leading from chamber 31 through suitable passageways such as 23 and 57 to. be more fully explained. The major components are disposed within the casing 19 and may be serially arranged in the fuel flow, the safety shut-off means 40 being disposed within the chamber 30 to control the fuel flow therethrough as by a valve 24 cooperating with an annular seat 28 disposed on the outlet side of said chamber. Posterior of the safety shut-off valve 24 and within the chamber 31 is the plug valve means 25 to be more fully described and which is adapted to manually control the flow of fuel to both the main and pilot burner outlets 21 and 22. Downstream of the plug valve means 25 and disposed within chamber 32 is the thermoelectrically powered main burner flow control means 50 comprising a valve 26 which coacts with a seat 27 to control the flow of fluid fuel to chamber 33 and outlet 21 leading to. the main burner 12.

Referring back to the safety shut-off means 40, the safety shut-off valve 24 may be controlled by a condition responsive operator means disposed within chamber 30 and comprises a generally U-shaped magnet core 41 disposed within and fixedlymounted with respect to a generally tubular casing 49 which in turn is mounted on a suitable depending bracket 45 attached to the interior of casing 19.' An energizing coil 42-may be disposed on core 41 which when energized is adapted to hold armature 43 in attracted relation when the latter is moved thereto. Means for energizing the coil 42 is provided by the thermoelectric generator 18 which is connected thereto by a pair of suitable conductors 7'1 and 72.

The safety shut-off valve member 2-4 is connected to the armature .43 for movement therewith by a suitable armature stem 46. A suitable depending guide bearing 29 is fixedly fastened to the interior of casing 19 to guide the armature stem 46 which is mounted for movement therein. Intermediate the ends of stem 46 and attached thereto is an upstanding annular lug 5 1. Interposed between lug 51 and the end surface of casing 49 is a biasing spring '44 which is disposed surroundingly to stem 46 to bias the armature 43 away from magnet 41 and valve 24 toward seat 28. It is to be noted that the distance between the armature 43 and magnet 41 is so great when the magnet 41 and armature 43 are in a separated relation, that even when the magnet 41 is energized it has insufficient attractive force to move armature 43 from its retracted position.

Means for resetting armature 43 toward attractive relation with magnet 41' is provided by a bell crank lever 53' and reset button 54. The :bell crank lever 53 may be pivotally mounted on the depending guide 29 and is formed with suitable extending lever arms 53a and 53b, the former engaging armature stem lug 51 and the latter engaging a reset stem 54a. Thus, upon depression of .Icset button 54 the end of reset stem 54a'engages lever arm 53b to move the latter in a clockwise direction to in turn cause movement of armature 43 toward engagement with the magnet 41. The reset button 54 and stem 54a may be biased upwardly by a suitable spring (not shown), and thus will return to the position shown in Figure 1 upon completion of the resetting operation.

The plug valve means 25 is positioned to control the fuel flow only when the safety shut-01f means 40 is cocked and energized and comprises a tapered rotatable plug 55 biased into a suitable complementary bored seat by a spring 63. The axis of the plug 55 and its seat is here shown transverse the axis of the bore forming chamber 31 and a part of chamber 32. The plug 55 may be formed with a relatively large diametric bore 56 transverse its axis for controlling registry with chambers 31 and 32. The lower portion of the plug may be formed with a relatively smaller coaxial bore 57 which communicates transverse bore 56 with a pilot outlet chamber 22a. A relatively small radial bore 58 (as best shown in Figures 4 to 7) is also formed transverse the axis of the plug to intersect bore 56 and provide an alternate passageway between chamber 31 and pilot outlet chamber 22a when the plug bore 56 is not in registry with chambers 31 and 32. Thus in the plug position shown in Figure 5, pilot gas may flow from chamber 31 to the pilot burner 14 through bores 58, 56, 57 and into supply pipe 15 even though flow of main gas is prevented by plug 55.

A low flow passageway for pilot gas is provided by a chordal slot or cut 59 which may be formed in the lower portion of plug 55 below bore 56 to connect chamber 31 to pilot outlet chamber 22a through passage 23 when said slot 59 is positioned to register with said passageway 23 and chamber 31. Metering means 69 may be disposed within pilot outlet chamber 22a for coaction with the end of passageway 23 to adjust the amount of fuel flowing through said passageway to control the low B.t.u. consumption position.

Means for manually rotating plug 55 is provided by an axially extending plug stem which projects outwardly of the casing 19 and terminates in a handle 62. The plug handle 62 may be formed with indicating means here shown as an arrow '67 which is adapted to register with suitable indicia means here shown formed on the exterior casing 19. A peripheral shoulder 62a may be formed on the plug handle 62 to define a surface for coaction with the reset button 54- the lip of which extends over said shoulder as best shown in Figure 3. A cylindrical peripheral surface 621) of the handle may be formed with a series of indentations 64, 65 and 66, indentation 64 permitting downwardly movement of button 54 when said indentation is aligned therewith. It is to be noted that indentations 65 and 66 (to be more fully explained) are smaller than indentation 64 and smaller than the amount of overlap of reset button 54 relative to shoulder 62a and hence reset movement of button 54 is prevented in all positions of the plug except when the button 5 4 and indentation 64 are aligned.

The main burner flow control means 50 controls the fuel flow to the main burner '12 only when the safety shut-off means is cocked and energized and the plug valve 55 is positioned so that bore 56 is in registry with chambers 31 and 32. The means for thermostatically controlling the main burner gas flow may be provided by a suitable thermoelectrically powered operator 73 which is preferably of the type that when energized will move valve member 26 to a fiowpermitting position, i.e. valve 26 away from seat 27. One terminal of the operator 73 may be connected directly to conductor 72 by conductor 74. The other terminal may be connected to conductor 76a, through a switch 75, conductor 76b, a suitable cycling thermostat 70 and to the conductor 71 at 77. It is to be noted that the high limit thermostat 60 is connected ahead of connection 77 so as to cause deenergiza tion of both the safety shut-off valve 24 and main burner valve 26 upon occurrence of an abnormal situation.

The switch 75 in the circuit to the main burner operator 73 is here shown attached to the outer housing thereof for coaction with the plug handle 62. The circuit is made and interrupted by a pin which is biased outwardly for coaction with peripheral surface 62b. The switch is preferably of the type that is normally closed and moves to a circuit breaking position upon registry with indentations 65 and 66 formed in the plug handle. Stated another way, except when the pin 80 is in registry with indentations 65 and 66, the circuit through switch 75 is closed. Thus it is seen that the circuit through switch 75 is closed when the plug is in the position shown in Figure 4 and open when the plug is in the positions shown in Figures 6 and 7.

The operation of the improved device is as follows:

Starting with the following initial conditions: the safety shut-off valve 24 positioned against seat 28 preventing all fuel flow to both the main and pilot burners, and the thermoelectric generator 18 cold. To start the device in operation, handle 62 is rotated to the reset position as shown in Figure 5, i.e. so that the arrow 67 points to reset. Reset button 54 is now in registry with indentation 64 permitting a downward reciprocatory reset movement of the button, which affords a clockwise movement of bell crank lever 53. Lever arm 53a is thereby moved into engagement with lug 51 causing armature 43 to be moved into engagement with magnet '41. Pilot gas is now permitted to flow through intersecting passageway 58, cross bore 56 and downward bore 57, pilot outlet chamber 22 and to supply pipe 15 for the pilot burner 14. Pilot burner gas is also permitted to flow through the low flow chordal slot 59, passageway 23 to pilot outlet chamber 22a. This position of the plug thus affords a relatively high flow of fuel for the pilot burner for ignition thereof, however, it is to be noted that no gas may flow to the main burner by virtue of the position of cross bore 56 which is out of registry with passageway 32. It is also to be noted that the peripheral plug handle indentation 66 is now in registry with pin 80 thereby opening switch 75 causing deenergization of operator 73 to thereby afford an alternative method of interrupting the flow to the main burner during reset operation.

Upon ignition of the pilot burner 12, thermoelectric generator 18 becomes heated and supplies sufficient thermoelectric energy to the energizing coil 42 to hold armature 43 in attracted relation to the pole faces of magnet 41 and valve 24 away from seat 28. Reset button 54 may now return to the position shown in Figure 1.

In normal wintertime operation of domestic furnaces when a high pilot flame is both necessary and desired, the plug valve handle 62 may be rotated to position shown as winter (as best shown in Figure 4). This position aifords a high fuel flow to the pilot burner 14 since both the high and low passageways are open, i.e. the chordal slot 59 is in registry with chamber 31 and passageway 23, and bore 57 receives fuel through bore 56. With the plug in the winter position, the main burner is under the control of the thermostat controlled thermoelectrically powered operator 73, the switch 75 being closed since pin 80 is held in its circuit closed position by surface 62b of the plug handle. Thus the main burner may now be cycled in response to the condition required by cycling thermostat 70.

In summertime or at other times when it is wished to maintain a constant burning pilot at a lower consumption rate, the plug handle 62 is rotated to summer po'sition, i.e. arrow 67 pointed toward summer position. (Plug will be as shown in Figure 6.) With the plug 55 in this position, the chordal slot 59 registers with chamber 31 and passageway 23 to provide a relatively low flow of fuel to the pilot burner 14, the exact amount of said flow being adjusted by the metering means 69. It is to be noted that the summer position of the plug positions cross bore 56 completely out of registry with chambers 31 and 32 thereby preventing all fuel flow to the main burner.

Further, no pilot fuel may flow through bore 57 since 7 neither bore 58 nor 56 registers with chamber 31'and hence the flow to thepilot is determined solely by the metering means 69 controlling the outlet of passage 23. It is also to be noted that the circuit to operator 73 is open since switch 75 is open due to the registry of pin 80 with indentation 65 in the plug handle.

When the plug handle arrow. 67 is aligned with the word a fourth position of the plug (as shown in Figure 7) is provided which shuts ofi all fuel flow to both the main and pilot .burners. Thus both A and B valve action is provided by the plug allowing a complete shut down of the fuel flow at this point in the system.

The apparatus provides increased economy by virtue of the fact that the pilot burner is operated in a manner to burn a minimum amount of fuel. This reduced consumption is at a level considerably'below that of conventional pilot burners and, in fact, is that minimum amount which will maintain a flame as distinguished from the higher rate of fiow required for initial ignition of the pilot burner, said higher rate being the minimum rate heretofore utilized. It will be observed that in the improved apparatus, the coaction between the reset button 54 and the shoulder 62a of the plug handle affords an interlock which insures that during resetting of the safety shut-ofi means the higher rate of fuel flow is supplied to the pilot burner for ignition thereof. Once ignited, however, the fuel flow to the pilot burner may be reduced, to the aforementioned minimum rate by rotation of the plug valve to the summer position. It is to be noted that no gas may flow to the pilot burner at any time unless the safety shut-off means is cocked and energized since the pilot supply is under the control of the safety shut-elf means 40, the latter being responsive to pilot outage. Thus the system shows a very low B.t.u. consumption pilot burner which may safely have a fuel flow in amount below that value which will support ignition, said fiame also being a selfregulated flame by virtue of the safety shut-off means 40.

The electrical interlock afforded by the opening of switch 75in the main burner operator circuit when the plug 55 is positioned in the low pilot (summer position) 7 makes possible a pilot burner flame that is'of very low consumption during standby situations while maintaining the pilot under safety shut-off control. For example, when the, plug valve is in either the winter position or the high pilot reset position, the pilot burner is producing a relativelylarge flame with consequent high heating value for impingement upon'the generator '18 due to the relatively large amount of fuel supplied to the burner 14.

The amount of heat produced by this relatively high pilot.

flame creates sufficient thermoelectric energy to satisfactorily fulfill the power requirements needed to operate both the safety shut-off operator and the main burner valve operator simultaneously. However, the low pilot position (summer) of the plug restricts the fuel flow to the pilot burner for low consumption purposes and consequently the pilot may produce insufficient flame heat for impingement upon the generator to supply the power requirements necessary to'operate both of the thermoelectrically powered valves simultaneously.:- In this latter type situation of alow heat producing flameat the pilot burner, in the absence of the interlock afiorded by switch 75, the closing of the contacts of room thermostat 70 would cause the circuit through the main burner valve 73 to be energized. This would result in deenergization of the safety shut-off control since there would be insuflicient power available from the generator to o'perate both valves. Thus it is seen that switch 75 prevents a false shut off of the safety shut-off'valve due to an inadvertent thermostat setting when the plug is positioned to' cause a low consumption pilot flame. A further feature afforded by the electrical interlock switch 75 in the summer low pilot position of the plug is that it provides a secondary prevention of fuel flow to main burner by assuring that valve 26 will remain against seat 27.- It is important that 8 no fuel flow to the main burner when the pilot is burning ata low consumption rate inasmuch as such a rate may provide a flame of insufficient strength to withstand ignition of the main burner and as such would be snuffed out by the main burner ignition.

Figure 2 illustrates an alternative form of control system wherein it is desired that the low flow pilot burner gas not be under the control of the safety shut-ofi valve. In this alternative system, .pilot passageway 23' is shown leading directly from chamber to the pilot outlet chamber 22a thereby providing a low pilot fuel flow independent of the safety shut-oif .valve. With this alternative embodiment, the flame impinging upon the generator at low pilot flow rate need not produce sufiicient energy in the generator to operate the safety shut-off valve. A B valve 100 is provided in this system to give manual cut off in a manner well understood in the art.

The alternative form of apparatus shown in Figure 8 illustrates a system that is especially adaptable for use in a range or oven control where 100% shut-off of the fuel is desired upon pilot outage but where the plug valve 55 doesnt shut off all pilot gas, i.e. the low flow passageway is not controlled by the plug. The low pilot passageway 2 leads directly from chamber 31" on the downstream side of the safety shut-off valve seat 28". In this system high fuel flow for pilot and main burner ignition is provided by means in the plug similar to, the means shown in Figure 1 so that the device is both economical and safe. In all other respects the system may be similar to the system shown in Figure 1, if desired.

Although a specific embodiment of the invention has been shown and described it is with full awareness that many further modifications thereof are possible. The invention therefore is not to be restricted except insofar as is necessitated by the prior art and by appended claims.

What is claimed by the invention is:

1. Control apparatus comprising, a main burner, a pilot burnerassociated with said main burner for ignition of the latter, said pilot burner alfording a flame suflicient to safely ignite said main burner when supplied with fuel at a first flow rate and affording a flame insuificient to safely ignite said main burner when supplied with fuel at a second lower flow rate, manually operable fuel control valve means operatively associated with said pilot burner and having a first open position permitting fuel flow to said pilot burner at said first rate and a second open position permitting fuel flow to said pilot burner at said second rate, resettable safety shut-off means operatively associated with said main and pilot burners to shut off fuel supplythereto upon outage of the pilot burner, means for manually resetting said safety shutoif means to fuel flow permitting position for reestablishment of a fuel supply to said burners, and means preventing resetting of said safety shut-off means except control means for controlling the fuel flow to said main burner, a source of electrical energy connected in circuit with both said control means-and having at least two output levels, a pilot burner operatively associated with said source of energy and having at least two heat output levels for respectively producing said two output levels in said source of energy, the electrical energy from said source at one level being sufiicient to activate both of said control means, and the electrical energy from said source at the other level being sufficient to activate only said first control means, means for cycling said second control means when the output of said source is at said one level, means for varying said heat output level of said pilot burner, said means having a first position affording said burner sufi'icient heat to safely ignite said main burner and also to produce said one output level in said source, said means having a second position affording said burner insufiicient heat to safely ignite said main burner but sufficient to produce said other output level in said source, and switch means mechanically interlocked with said output varying means and having contacts in the energizing circuit for said second control means for interrupting the latter when said output varying means is in its said second position.

3. In combination, fluid fuel burning apparatus having a main burner and a pilot burner operatively associated therewith, a manually operable pilot fuel control valve having a closed position shutting off all pilot fuel flow, having a low pilot position permitting fuel flow to said pilot burner at a rate to produce a flame thereat incapable of safely igniting said main burner, and having a high pilot position permitting fuel flow to said pilot burner at a rate to produce a flame thereat capable of safely igniting said main burner, an electroresponsive main burner fuel valve having an energizing circuit, and switch means mechanically interlocked with said manual valve and having contacts in said energizing circuit for interrupting the latter when said manual valve is in said low pilot position.

4. In combination, main and pilot burners, manually resettable safety shut-off fuel flow control means for at least one of said burners, second fuel flow control means operatively related to said pilot burner and having low and high fuel flow permitting positions with respect thereto operable at said low position to supply sufficient fuel to said pilot burner to support a stable flame thereat but insufficient for initial and sustained ignition thereof, and operable at said high position to supply suflicient fuel to said pilot burner for initial and sustained ignition thereof, and means permitting manual resetting of said resettable safety shut-oft control means to fuel flow permitting position only when said second fuel flow con trol means is in its said high fuel flow permitting position.

5. In combination, main and pilot burners, manually resettable safety shut-off flow control mean having flow preventing and flow permitting positions with respect to said main and pilot burners, fuel flow controlling means operatively related to said pilot burner having low and high fuel flow permitting positions with respect thereto operable at said low position to supply sufficient fuel to said pilot burner to support a stable flame thereat but insufi'icient for initial and sustained ignition thereof, and operable at said high position to supply sufiicient fuel to said pilot burner for initial and sustained ignition thereof, and means preventing manual resetting of said resettable safety shut-ofi control means from flow preventing to flow permitting positions when said fuel flow controlling means is in its said low fuel flow permitting position.

6. In combination, main and pilot burners, resettable safety "shut-off control means controlling fuel flow to said pilot burner, fuel flow controlling means operatively related to said pilot burner having a first position operable to supply sufficient fuel to said pilot burner for initial and sustained ignition thereof and a second fuel flow permitting position operable to supply a lesser amount of fuel that is suflicient to support a stable flame at said pilot burner but in amount insufficient for initial and sustained ignition thereof, and manual reset means operable to reset said resettable safety shut-ofi control means to fuel flow permitting position only when said fuel flow controlling means is in its first position.

7. Control apparatus comprising manually resettable electroresponsive safety shut'otf first control means, cycling electroresponsive second control means having a pull-in energization requirement substantially greater than the hold-in energization requirement of said resetta ble control means, a heat responsive source of energy connected to said first and second control means and having first and second output levels, a fuel burner operatively associated with said source of energy and having at least two heat output levels for respectively producing said two energy output levels in said source of energy, energy from said source at said first output level being of suflicient magnitude to supply said first and second control means with said hold-in and pull-in energization requirements respectively, and energy from said source at said second level being of sufiicient magnitude to supply only the hold-in energization requirement of said first control means, and manually operable means controlling all fuel flow to said burner and operable selectively to prevent fuel flow thereto or to vary said fuel flow and thereby vary the heat output level of said burner, said manually operable means being movable to a position causing said burner to produce one level of heat in response to which said first and second control means are respectively supplied with said hold-in and pull-in energization requirements by the output of said source, said manually operable means also being movable to another position causing said burner to produce a second level of heat in response to which only the hold-in energization requirement of said first control means is supplied by the output of said source.

8. Control apparatus comprising manually resettable electroresponsive safety shut-off first control means, cycling electroresponsive second control means having a pull-in energization requirement substantially greater than the hold-in energization requirement of said resettable control means, a heat responsive source of energy con nected to said first and second control means and having first and second output levels, a fuel burner operatively associated with said source of energy and having at least two heat output levels for respectively producing said two energy output levels in said source of energy, energy from said source at said first output level being of sufficient magnitude to supply said first and second control means with said hold-in and pull-in energization requirements respectively, and energy from said source at said second level being of sutficient magnitude to supply only the hold-in energization requirement of said first control means, and manually operable means controlling all fuel flow to said burner and operable selectively to prevent fuel flow thereto or to vary said fuel flow and thereby vary the heat output level of said burner, said manually operable means being movable to a position causing said burner to produce one level of heat in response to which said first and second control means are respectively supplied with said hold-in and pull-in energization requirements by the output of said source, said manually operable means also being movable to another position causing said burner to produce a second level of heat in response to which only the holdin energization requirement of said first control means is supplied by the output of said source, and means mechanically interlocked with said manually operable means for interrupting the circuit between said cycling control means and said source when said manually operable means is in its said other position.

9. Control apparatus comprising, a main burner, a pilot burner associated with said main burner for ignition of the latter, said pilot burner affording a flame suflicient to safely ignite said main burner when supplied with fuel at a first flow rate and affording a flame in sufficient to safely ignite main burner when supplied with fuel at a second lower flow rate, manually operable control valve means having an inlet and having a pair of outlets connected to said main and pilot burner respectively, said valve means having a pair of fuel passages communicating between said inlet and the outlet connected to said pilot burner, said valve means having a single valve member controlling all fuel flow from 11 said inlet to said outlets selectively movable to a closed position shutting off all fuel flow to said burners, and to first, second and third open positions, said first posi: tion permitting fuel 'flow from said inlet to said pilot burner only and through both of said fuel passages to afford pilot fuel flow at said first rate, said second position permitting fuel flow from said inlet to said pilot burner only and through only one of said fuel passages to afford pilot fuel flow at said second rate, and said a third position permitting fuel flow from said inlet to said main burner and through both of said fuel passages to afford fuel flow at said first rate to said pilot burner.

lOyControl apparatus comprising, a main burner, a pilot burner associated 'with said main burner for ignition of the latter, said pilot burner affording a flame sufiicient to safetly ignite said main burner when supplied with fuel at a first flow rate and affording a flame insuificient to safely ignite said main burner when supplied with fuel at a second lower flow rate, manually operable fuel control valve means having an inlet and having a pair of outlets connected to said main and pilot burners respectively, said valve means having a single valve member controlling all fuel flow from said inlet to said outlets selectively movable to a closed position shutting off all fuel flow to said burners, and to first, second and third open positions, said first position permitting fuel flow from said inlet to said pilot burner only and at said first rate, said second position permitting fuel fiow from said inlet to said pilot burner only and at said second rate, and said third position permitting fuel flow from said inlet to said main burner and at said first rate to said pilot burner, resettable safety shut-ofi means operatively associated with said main and pilot burners to shutoff fuel supply thereto upon outage of said pilot burner, means for manually resetting'said safety shut-off means to fuel flow permitting position for a reestablishment of a fuel supply to said burners, and means preventing resetting of said safety shut-01f means except when said valve means is in said first position so that reestablishment of fuel flow to said pilot burner can be efiected only at said first flow rate.

References Cited in thefile of this patent UNITED STATES PATENTS 1,968,319 Shively July 31, 1934 2,081,091 Kuempel May 18, 1937 2,384,696 Ray Sept. 11, 1945 2,478,386 Gauger Aug. 9, 1949 2,566,372 Ray Sept. 4, 1951 2,588,179 Thornbery Mar. 4, 1952 2,746,472 Sogge May 22, 1956 

